The present invention relates to a movable contact holder mounted on electrical apparatus, for example, an electromagnetic contactor and an assembling method thereof.
As is well known, an electromagnetic contactor is provided with a movable contact holder having bridge contact assemblies, each being made opposite to a stationary contact assembly of a contact mechanism connected to a main circuit, mounted on a movable contact holder base of insulator material (molded resin) to be held therein while each being made combined with a contact spring (a compressed coil spring pressing the bridge contact assembly against the stationary contact assembly to apply a contact pressure to the contact faces of both of the bridge contact and the stationary contact with both of the contacts being made closed). The movable contact holder is coupled to a movable core of an operation electromagnet to be driven to either one of ON and OFF positions for closing and opening, respectively, the contacts by controlling an electric current flowing in the coil of the electromagnet.
The driving systems of the movable contact holder may be classified into vertical slide systems and horizontal slide systems. A vertical slide system is one in which the movable contact holder is operated to slide up and down to open and close the contacts. A horizontal slide system is one in which the movable contact holder is operated to slide side to side to open and close the contacts. For the latter horizontal slide system, the system of the electromagnetic contactor disclosed in FIG. 1 in JP-A-10-223431, for example, is publicly known. In the electromagnetic contactor disclosed in FIG. 1 in JP-A-10-223431, an electromagnet is of a support type, in which a movable contact holder is to be operated so as to slide side to side with the top end of a lever of a movable core, moveably coupled to a fixed core by a hinge, coupled to the movable contact holder. Moreover, an arrangement is also known in which, instead of the support type electromagnet, an ordinary leg type or plunger type electromagnet is horizontally laid under a movable contact holder to connect the movable core and the plunger of the electromagnet to the movable contact holder by an operation lever of a separated component so as to operate the movable contact holder to slide side to side.
Next to this, about the electromagnetic contactor disclosed in FIG. 1 in JP-A-10-223431, the structure of a movable contact holder mounted thereon will be explained with reference to FIG. 10. Moreover, an assembling method of the movable contact holder, by which method bridge contact assemblies and contact springs are attached to a movable contact holder base, will be explained with reference to FIGS. 11A to 11E.
First, in FIG. 10, a movable contact holder 1′ has a movable contact holder base 1″ of a molded product of resin, bridge contact assemblies 2 each corresponding to a main circuit contact assembly, bridge contact assemblies 3 each corresponding to an auxiliary contact assembly, bridge contacts 2a each provided at each end of the bridge contact assembly 2, bridge contacts 3a each provided at each end of the bridge contact assembly 3 and contact springs (compressed coil springs) 4. The movable contact holder base 1″ has a plurality of square openings 1a opened in a line in the lateral direction in a laterally long block. In each of the square openings 1a, the bridge contact assembly 2 or 3 is inserted to be held transversely to the lateral direction while being paired with the contact spring 4 as illustrated. Reference numeral 1b denotes a protrusion that indicates an operating state of the electromagnetic contactor, namely, whether the electromagnetic contactor is turned-ON or turned-OFF. Reference numeral 1c denotes a channel into which a top end of an operation lever is fitted which is coupled to a movable core of an electromagnet (not shown).
While, in the process of assembling the movable contact holder 1′, the bridge contact assemblies 2 and 3 and the contact springs 4 are to be attached to the movable contact holder base 1″ by the working steps as shown in FIGS. 11A to 11E. Namely, in the initial assembling processes, the bridge contact assembly 2 is inserted into the square opening 1a from the side of the movable contact holder base 1″ with the surface of the bridge contact assembly 2 being made a little inclined from the vertical direction (see FIGS. 11A and 11B). Subsequent to this, the state of the bridge contact assembly 2 inserted into the square opening 1a is returned to its original state so that the face of the bridge contact 2a of the bridge contact assembly 2 becomes vertical before the bridge contact assembly 2 is brought to the one end side of the square opening 1a (see FIG. 11C). Then, as shown in FIG. 11D, the contact spring (compressed coil spring) 4 in a free length is compressed and then, with the compressed state being kept as it is, pressed or inserted sideways into a space between the side wall surface inside the square opening 1a and the bridge contact assembly 2 to be made fitted to the space. The state in which the bridge contact assembly 2 and the contact spring 4 are attached to the movable contact holder base 1″ is shown in FIG. 11E. Further, with the same procedure as the foregoing, the remaining pairs, each with the bridge contact assembly 2 or 3 and the contact spring 4, are inserted into the square openings 1a of the bridge contact assembly base 1″ one by one in succession, by which the movable contact holder 1′ is completed. In the present status, the assembling work of the movable contact holder 1′ is entirely carried out manually.
Recently, in order to increase productivity and reduce manufacturing expenses, automation of parts assembly is expanding by introducing assembly robot systems into manufacturing lines of electric apparatus. In the movable contact holder 1′ with the related structure shown in FIG. 10, when the bridge contact assemblies 2 and 3 and the contact springs 4 are attached to the movable contact holder base 1″, as was explained about the assembling method shown in FIGS. 11A to 11E, there are required the steps of inserting the bridge contact assemblies 2 and 3 and the contact springs 4 sideways into the small square openings 1a opened in the movable contact holder base 1″. However, for carrying out the insertion steps with an automated machine, there is a limitation due to handling of the components with minute external shapes. Namely, it is considerably difficult for an automated machine to pick up and attach the contact spring 4 as a minute component to the movable contact holder base 1″ by pressing or inserting the spring 4 sideways into the narrow space while the spring 4 is compressed. This problem has been preventing the automatization of such assembling from being brought into realization.
In view of the above, it would be desirable to provide a movable contact holder with an improved structure that would enable automatic assembly of even minute components.